Master bomb-maker was creating undetectable explosives

French jihadist David Drudgeon was one of the most active bombmakers with in the Khorasan group, sources tell CNN. Drudgeon was allegedly killed in a U.S. air strike Thursday morning.

His knowledge of explosives, European-background and access to Western fighters in Syria makes him arguably one of the most dangerous terrorists in the world.

His mission was apparently to create very small, non-metallic explosive devices that could be smuggled through airport security and onto a U.S.-bound plane, where it would be assembled to blow up the airplane.

Drudgeon was working on a variety of bombs, sources tell CNN, that could be easily disguised in everyday objects, such as cell phones and toothpaste tubes.

CNN's Pamela Brown reports.